Semiconductor devices are increasingly being used in consumer, commercial and other electronic devices. The semiconductor devices may be classified into a memory device for storing data, a logic device for processing data, and a hybrid device including both of memory and logic elements. To meet the increased demand for electronic devices with fast speed and/or low power consumption, it may be necessary to realize semiconductor devices with high reliability, high performance, and/or multiple functions. To satisfy these technical requirements, complexity and/or integration density of semiconductor devices are being increased.
A double patterning technology is used to form fine patterns having a dimension smaller than a minimum feature size which an exposure apparatus can print. For example, in order to form such fine patterns, a conventional double patterning process may include steps of forming a spacer on a sidewall of a sacrificial pattern using photolithography and etching processes, of removing the sacrificial pattern, and of etching a to-be-etched layer using the spacer as an etch mask. However, as an integration density of a semiconductor device increases, it may be necessary to develop patterning methods allowing patterns to have a smaller size than that of the double patterning process.